Asked if that was an unlikely scenario and if any surprised burglar would simply run away, Mr Rowley said: "In my experience, if you try to apply the cold, rational logic of a normal person sitting in their front room to what criminals do under pressure, you tend to make mistakes.

"It was a sensible hypothesis and it's not entirely ruled out."

Madeleine disappeared as she slept in a room with her younger twin siblings while their parents Kate and Gerry McCann, both doctors, dined with friends nearby.

Scotland Yard began investigating six years ago after the failure of the first Portuguese police investigation. The team of detectives, cut in 2015 from 29 to four, has spent more than £11m of UK Government funds.

Mr Rowley said new information was still being received daily.

The Metropolitan Police was recently given an extra £85,000 by the Home Office to keep the investigation going until September.

Portugal's deputy national director of the Policia Judiciaria, Pedro do Carmo, told Sky News that he was under no financial or political pressure to wind up his re-opened investigation.

He said: "If the Metropolitan Police decides to close its investigation that doesn't mean we are going to close ours.